Car refrigeration



Det; 10, 1935. D P. MlNARD GAR REFRIGERATION Filed NOV. 9, 1934 2 Sheet-s-Sheet 1 J5 j; Y l@ 1.

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Dec' 10 1935 D. P. MINARD CAR REFRIGERATION Filed No'v. 9, 1954 2 sheets-sheet 2 fra/fa? au@ lgjwfzazfd,

Patented Dec, 1o, 1935 UNiTED STATES PATENT OFFICE can nnmrcm'rlon f David P. annua, chicago, nl., signor to Armour and Company, Chicago, lll., a corporation oflllinols This invention relates to car refrigeration, the

present application being in part a continuation of application for Letters Patent of the United States iiled by me May 14, 1934, Serial No. 725,514.

The object of the invention is to provide a method of refrigerating cars by which the period of refrigeration is prolonged and the degree of re-A frigeration obtained is increased over the methods now commonly employed.

A further object of the invention is theprovision of a method for the purpose indicated by which the air within the car is more uniformly treated andv` the refrigerating agentV utilized to vgreater advantage than in the present methods.

The invention also aims to provide a method of car refrigeration by which greater economy in the costsof operation and in the cooling agents employed is attained.

As a further object of the invention the latter has in view the provision of a method that is the interior hardware of the car is much less likely to be a'dversely aiected.

Other objects and advantages will appear as the nature of the improvements is better understood, the invention consisting in the novel method hereinafter described, illustrated in the accompanying drawings, and nally pointed out in the appended claims.

A preferred adaptation of the invention is' presented herein for the purpose of exemplication,

but it will be understood that the invention is capable of being practiced or utilized in other modied forms which come equally within the scope of the appended claims, wherefore the drawings and description are to be taken in an illustrative and not in an unnecessarily limiting sense. f

In the accompanying drawings,

Fig; 1 shows in vertical longitudinal section on end of arefrigerator car illustrating the tanks filled with ice as in the initial stage of treatment in accordance with the present invention;

Fig. 2 is a similar view illustrating the iced tanlm iilled withk a low temperature cooling agent designed to cooperate with the ioe in the further practice of the method;

Fig. a is intended to mostrate .the ongmog p f theiceinthetanksafterapeodof timehas elapsed and a portion of the ice has melted; V Fig. 4 is a transverse section through one end of the car and the battery of ice tanksv at that end.

, The cooling agents which are preferred for use in practicing the herein described method comprise crushed ice and salt to which is added a o brine, but pre-frozen eutectic mixtures, such as slush brine or ribbon ice, without thesubsequent 10 addition of any liquid, may be employed, as may also any other medium adapted for the purpose.

Referring to the drawings, the wall of the refrigerator car is shown at II', the ioor at I2, and the roof at I3. Within each end of the car is 15 arranged the usual battery of ice tanks I4, which tanks may be provided adjacent their lower ends, or at any other suitablepoints, with properly controlled outlets for draining the same. The tanks I4 in ordinary practice are supplied with ice from 20 above through openings which are provided with hatches I5. The tanks are separated in theusual manner from the lading space of the car by a protective 'bulkhead I6. This bulkhead preferably is spaced from the ceiling and iioor of the 25 car, so as to function as an air-guiding baille which is eiective to permit the warm air in the carzto move into contact with the tanks at the top of the car, and thereafter retain the air in intimate association with the exterior surfaces of the i oor of the car. The construction thus far described is that which is found in many present day refrigerator cars of approved design. The present invention may be practiced advantageously with a car of this type, but it is not in its application and may be used with other cars of somewhat different types.

that a cooling surface on the tanks equivalent to practically the entire surface thereof is continuously maintained, as distinguished from the effect of ice and salt mixtures ordinarily emtive cooling surface. For example, it might be said that whenvthe ice is dissipated to the extent of 50%, the effective cooling surface of the tanks may be reduced 60% to 70%. By the addition of the brine, however, when the ice is dissipatedto the extent of 50% the cooling surface still remains the same as at the start by reason of the remaining ice floating on the top of the brine,

Y which condition`is illustrated in Fig. 3, and the natural convection currents set up inv the brine beneath the 'ice acting with the ice to maintain the mixture at a continuous low temperature. It follows, therefore, that the walls of the tanks I4 present, in their entirety,` chilled surfaces to the air within the car, and that the air, by convection, circulates throughout the interior of the car andreduces the temperature thereof to the desired point for the attainment of the chilling conditions that are sought. In such circulation the air currents pass through the opening at the top of the bulkhead I6 and flow downwardly between the bulkhead and the outer walls of the tanks. Upon reaching the floor of the car about the tanks the cooled air will move back into the car interior along the floor and walls. As the air passes over the walls and oor it extracts heat which increases 'the temperature o f the circulating air and causes it to rise and establish convection currents within the car. These currents act to carry the heated air along the roof of the car towards the opening between the bulk# head and the tanks and therebyV complete the cycle.

The filling of the tanks with the ice constitutes the charging stage of the herein described method and imparts an initial lowering of the temperature of the tanks. When the brining stage follows, as when-the tanks are filled with the brine to cover completely the ice introduced in the charging stage, there is created a material reduction in the temperature of the tanks. The melting of the ice induces further reduction in the temperature of the mixture, and during such melting the ,ice floats in the brine vto the top thereof, as indicated in Fig. 3. But the entire liquid body within the tanks is effective to maintain the low temperature of the tanks, and the entire surface of the latter thereby is exposed for contact by the convective air currents in their circulation. This attains a degree of refrigeration that is greatly increased over the methods now commonly employed, and the period of eifective refrigeration likewise is prolonged. Due to the large expanse of contact surfacevof the tanks the air within the car is more uniformly treated and the refrigerating agent utilized to greater advantage than in the present methods. The air within the car will. circulate between and around the articles of lading and over the surfaces of the tanks, thereby maintaining the desired low temperature until the charge of ice within the tanks hasbecome depleted.

To illustrate the advantages and novelty of this invention the results of some actual shipments of fresh meats following the methods as outlined above are cited. In one case cars were shipped from Chicago to New York in summer and unloaded at the destination after a total elapsed time, from the time the car was closed at the loading dock until it was unloaded, of from to 120 hours. 'I'he product arrived in good condition. The cars had internal temperatures of 34 to 36 F. when opened for loading, and throughout the entire journey the temperature increase was held to a maximum of '6 to 8 without any re-icing of the cars in transit, whereas the usual practice in handling cars required that the cars be re-iced at four stations enroute and once at the destination. In this case the average outdoor temperature during the run was '19.5 with a maximum of 105.0 F.

In another case, a shipment of cars loaded with fresh meats was made from Omaha to New York without any re-icing in transit during which run the average outdoor temperature was 84.6 with a maximum of F. without any re-icing after leaving the shipping point. All product unloaded in good condition at car temperatures ranging from 41 to 43 F.. which represents a car interior temperature rise of 6 to 8. 'Ihe elapsed time from loading to unloading was from 85'to 95 hours. The re-icings requiredin transit by cars shipped in the same train but prepared in the usual manner amounted to five, which in the case of the specially prepared cars were entirely eliminated.

With cars shipped by the method of the present invention a gradual rise in interior temperature is experienced. Over the range oftemperatures indicated this rise in-temperature does no harm to the product in the car. In cars shipped by the usual methods of refrigeration, after each icing a more or less rapid rise in temperature is exerienced, up to the time of the next re-icing. e re-icing causes the temperature to fall, thus starting up a cycle of temperature variations, each subsequent re-icing representing a cycle. Although the temperature variation range may be no greater than the total temperature rise of the specially prepared cars, the continued repetition of temperature variations adversely affects the product. This damaging influence is not present in cars refrigerated in accordance with the present invention as their temperature rise' is through one cycle only.

While the invention has been described in its application to refrigerator cars, itis obvious that the same is adaptable to automobile refrigerator S trucks without departing from the essential characteristics of the invention in its application to refrigerator cars, and it is to be understood that such extendedapplication is within the purview of the invention.

As an alternative arrangement for obtaining the desired low temperature area exposed for contact by the air currents, the level of the outlets -of the tanks H may be such that the space in the tanks below that level will contain sufficient brine that the displacement of the ice, when added, will raise the brine level to such a point as to give an inside wetted surface equal to or closely approaching the area of wetted surface that is obtained by adding brine to the tanks after they are iced, as shown in Fig. 2.

My invention further contemplates the pre- Acooling or conditioning of refrigerator cars by the provision of a low temperature refrigerant maintaining a wetted cooling surface on the tanks I) Il lent to substantially the entire area of the surequivalent substantially tothe entire surface thereof. To this end, brine or other low temperature refrigerant may be provided in the tanks in quantity` suilicient to cover the charge of ice and salt, or pre-frozen eutectic mixtures such as slush brine or ribbon ice may be employed without the subsequent addition of any liquid, wherebythe walls of the tanks are continuously maintained over substantially the entire area at a reduced 4temperatureand present a maximum surface for the absorption of heat from the car interior. As a. specic example of such precooling, the tanks may rst be charged with ice and salt or other meltable refrigerant, as in Fig. A

1, and may then be lled with brine or other nonfreezing liquid completely covering the ice or meltable refrigerant as in Fig. 2. During the cooling of the car, if ice is used, the ice melts and oats in the upper portion of the brine or other non-freezing liquid, as indicated in Ng. 3, the effective cooling area of the tank wells, however, being maintained undiminished due to the continuous contact of-the brine therewith; the natural convection currents set up in the brine .or other non-freezing liquid beneath the ice or other meltable refrigerant, moreover, coaeting with the ice to maintain the e ata continnous low temperature, and the brine' or other non-freezing liquid filling the voids between the ice and the tank walls and providing for uninterrupted transm'ssion of heat from the car through said walls and to said ice or to the meltable refrigerant. After the desired pre-chilling has been attained, the tanks may be replenished as desired; to which end the 'brine or other rion-s freezing liquid may be withdrawn from the tanks until only cient brine or other non-freezing liquid remains in the tanks to completely nil the voids between the ice or other meltable refrigerant particles when the tanks are se- -quently recharged with ice or other meitable refrigerant as required to replace the ice or other meltable refrigerant melted during the pre-coolring period. Pre-cooling in the manner hereinbefore described may be accomplished with' marked emciency and in substantially shorter periods than in prior practice, owing to the maintenance of a continuously cool surface on the tank walls and to the elimination of air gaps between the interior surfaces of said. walls and the refrigerant in the tanks.

Although the procedure recited in the foregoing description provides for rst charging the tanks with ice and salt `or other meltable refrigerant fully charging the tanks with ice and salt or other meltable refrigerant.. In either instance the tanks will contain the full capacity of ice and salt or other meltable refrigerant plus the brineor other non-freezing liquid necessary to ll the voids between the ice or other meltable refrigerant particles.

s the present invention, it provides a method for refrigerating cars, whether for transit or for pre-cooling the same for transit.

Iby incorporating into the tanks a charge ofice,

salt and preformed low temperature liquid sumcient to cover the ice completely; or by charging the tanks'withol preformed eutectic mixture,`

such as slush brine or ribbon ice, without the addition of any liquid. A cooling surface equivaface of the tanksis thereby maintained and gaps or interstices occurring between unmelted particles of the meltable refrigerant in the tanks are filled with the low temperature liquid, whereby 5 heat from the car interior may be continuously and eiiiciently transmitted through the tank walls to the refrigerant without interruption by the presence of air gaps between the tank walls and the refrigerant particles. 10

I claim:

1. The method of refrigerating cars, which consists in charging the cooling tanks thereof with a quantum of ice, adding thereto a heat transmitting liquid, and maintaining flotation of 15 the ice within the tanks during meltage without diminishing the volume of the liquid contentsof the tanks, whereby to maintain a cooling surface on the tanks equivalent to substantially the entire surface thereof. 2o

2L The method of refrigerating cars, which consists in charging the cooling tanks thereof with a quantum of ice, ad thereto a low temperature liquid in sumcient volume to cover the ice consists in charging in@ tanks thereof with the ice or other refrigt used, then filling the charged n 1: with a low temperature liquid, and maintaining notation of the ice or other refrig-v r the volume of the liquid contents of the t, whereby to :n on the tanks equivalent to substantially the en tire surface thereof. 4. The' method of refrigerating cars, which consists in `cthe cooling tanks thereof with a quantum of ice, adding thereto a liquid, and 45' main notation of the ice within the tanks during meltage 'without the volume of the liquid contents of the tanks, thereby to maintain a cooling surface on the tanks equivalent to substantially the entire surface thereof. 5o 5. The method of refrigerating cars, which comprises introducing into the*- cooling tanks thereof a cooling liquid of suiciently low temperaturetoimparttothewallsofthetanksa desired reduced temperamre, and maintaining 5.;

the liquidcontents of the tanks at reduced temperature to a cooling surface von the tanks equivalent to substantially the entire surface thereof. i

6. The method of refrigeratingcars, ywhich 6o comprisesbharging a tank thereof with a melt-A able refrigerant and maintaining in a wetted conditionsubstantiallytheentireinnerareaofa' Awall of said tank during the melting of said refrigerant.

7. The method of refrigerating cars, which comprises charging a tank thereof with a meltable refrigerant and maintaining a vheat transliquid in such volume to occupy during melting of said refrigerant substantially all spaces between the unmelted refrigerant and the wall of said tank for continuously transmitting heat from said car to the unmelted refrigerant, meanwhile maintaining flotation of the mimelted'ii'efriger- 75 tain a cooling surface 4o ant in saidtank without decrease in volume of the tank'contents.

8. The method of refrigerating cars, which comprises charging a tank thereof with a meltable refrigerant and maintaining a `heat transmitting liquid in said tank in volume sufficient to provide a' continuously wetted surface over substantially the entire area of a wall of said tank during the melting of said refrigerant and to preclude the formation of air gapsbetween unmelted refrigerant and the inner walls of said tank during melting of said refrigerant.

9. The method of refrigerating cars, which comprises charging a tank thereof with a meltable refrigerant and maintaining in said tank during melting thereof a low temperature liquid in contact with a wall of said tank to a height substantially equal to that of the highest unmelted refrigerant in said tank, meanwhile maintaining flotation of the unmelted refrigerant in said tank without decrease in volume of the tank contents.

10. The method of refrigerating cars, which comprises charging a tank thereof with a meltable refrigerant and adding thereto a preformed low temperature liquid to maintain a continuously wetted cold surface on the interior of said tank duringmelting of said meltable refrigerant.

11. The method of refrigerating cars, which comprises charging a, tank thereof with a meltable solid refrigerant and adding thereto a preformed low temperature liquid in volume suiicient to preclude the formation of air gaps between the solid refrigerant and the interior walls of said tank during melting of said solid refrigerant.

12. The method of refrigerating cars, which comprises charging a tank thereof with a meltable solid refrigerant and -adding thereto a preformed low temperature liquid in volume sufficient to substantially cover said solid refrigerant and to maintain a continuously wetted surface over substantially the entire inner area of a wall of said tank during melting of said solid refrigerant.

13. The method of refrigerating cars, which comprises charging a tank thereof with ice and adding thereto a preformed liquid of such character and in such volume as to continuouslytransmit heat from the car to said ice despite melting of the ice out of contact with the walls of said tank.

14. The method of refrigerating cars, which comprises charging a tank thereof with ice and maintaining in said tank a low temperature liquid formed prior to the insertion of said ice in such volume as to substantially lill all spaces between the unmelted ice and the walls of said tank during melting of said ice and thereby to transmit heat from the car to said ice.

15. The method of refrigerating cars, which comprises charging a tank thereof with ice andl salt, and also with a low temperature liquid of sufficient volume'to fill substantially all gaps between the ice and the walls of said tank during melting of said ice and thereby to transmit heat continuously from said car to said ice.

16. The method of refrigerating cars, which comprises charging a tank thereof with ice and salt and also with a low temperature liquid in volume sufficient to substantially completely cover said ice. A

17. 'I'he method of refrigerating cars, which comprises providing in a tank thereof a low temperature liquid and thereafter inserting therein a meltable refrigerant, the quantities of said liquid and said refrigerant being such-that the introduction of said refrigerant causes said liquid to rise sufficiently to ll substantially all spaces between said refrigerant and the walls Aof said tank during melting of said refrigerant. 5 18. The method of refrigerating cars, which comprises providing in a tank thereof a low temperature liquid and thereafter inserting therein a meltable refrigerant, the quantities of said liquid and said refrigerant being such that the introduction of said refrigerant causes said liquid to rise to such extent as to maintain on an inner surface of a wall of said tank duringmelting of said'refrigerant a wetted area of a height substantially equal to the maximum distance of any part of said refrigerant from the bottom of said tank.

19. The method of refrigerating cars, which ycomprises charging a tank thereof with a melt' able refrigerant and also with a low temperature liquid of such quantity as to maintain contact with the inner surface ofv a wall of said tank over substantially the entire area thereof throughout melting of said refrigerant.

20. The method of refrigerating cars, which consists in charging the cooling tanks thereof with a quantum of ice, providing therein a low temperature liquid formed independently of said ice to reduce the temperature of the walls of the tanks, and maintaining flotation of the ice Within the tanks during meltage without diminishing the volume of the liquid contents of the tanks, whereby to maintain a cooling surface on the tanks equivalent to substantially the entire surface thereof.

21. The method of refrigerating cars, which consists in charging the cooling tanks thereof with a quantum of ice, providing therein a low temperature liquid formed independently of said ice in suilicient volume to cover the ice in the tanks and thereby reduce the temperature of the walls of the tanks, and maintaining flotation of the ice within the tanks during meltage `without diminishing the volume of the liquid contents of the tanks, whereby to induce convective currents in the liquid and maintain a cooling surface on the tanks equivalent to substantially' the entire surface thereof.

22. The method of refrigerating cars, which consists in charging the cooling tanks thereof with a quantum of ice, adding thereto a low temperature liquid to reduce the temperature of the walls of the tanks, and maintaining flotation of the ice within the tanks during meltage without diminishing the volume of the liquid contents of the tanks, whereby to maintain a cooling surface on the tanks equivalent to substantially the entire surface thereof.

23. The method of refrigerating cars, which consists in charging the cooling tanks thereof with a quantum of ice, adding thereto a low temperature liquid in sufficient volume to cover the ice in the tanks, and thereby to reduce the tem perature of the walls of the tanks, maintaining flotation of the ice within the tanks during meltage without diminishing the volume of the liquid contents of the tanks, whereby to induce con,

vective currents in the liquid and maintain a cooling surface on the tanks equivalent to subtaining flotation of the ice within the tanks during meltage without diminishing the volume of theliquid contents ofthe tanks, wherebyto induceconvective currents in the liquid and maintain a cooling surface on the tanks equivalent to substantially the entire surface thereof, then removing a portion of the liquid contents of the tanks, and re-icing the tanks to the extent required for lling the same.

25. A cooling unit for use in arefrigerator car,

. consisting of a refrigerant tank or container l consisting of a refrigerant tank or container adapted to be located in the end ofja car, said tank having a solid refrigerant therein, and a liquid surrounding the solid refrigerant in sumil cient quantity tol iill all voids in the refrigerant mass and to substantially fill said tank. l 27. A cooling' unit for use in a refrigerator car," consisting of a refrigerant tank or container adapted to be locatedin the end of a car, said tank having a charge of ice therein, and a' liquid surrounding the ice in suilicient quantity to ll all voids in the ice mass and to substantially ll said 28. A cooling unit for use ina refrigerator car,

Aconsisting of a refrigerant tank or container' adapted to be ,located-in the end of a car, said tank having therein a charge of broken ice, and a quantity of brine sumcient to illl all voids be-v tween the ice fragments and to substantially ll saidtankm- DAVID P. MINARD. 

